Strand handling apparatus



I May 16, 1944. J. N. SELVIG 2,343,356

STRAND HANDLING APPARATUS Filed Dec. 22, 1942 FIG. I

INVENTOR J.N. SEL VIG Patented May 16, 1944 STRAND HANDLING APPARATUSJohn N. Selvig, Westfield, N. J., assignor to Western Electric Company,Incorporated, New York, N. Y., a corporation of New York ApplicationDecember 22, 1942, Serial No. 469,791

' Claims.

This invention relates to strand handling apparatus, and moreparticularly to apparatus for imposing tension upon a longitudinallyadvancing strand.

There are, innumerable instances in the various arts which deal withstrands, such as threads, strings, wires and the like, in which a strandis drawn through some apparatus, e. g. by a capstan, a pair of drivingrolls between which the strand runs, a take-up spool or reel, or otheradvancing means, from a supply reel, supply cop, or other equivalentsupply means, which latter offers no resistance to the removal of thestrand therefrom. In many such cases it is of importance that means beprovided to hold the strand yieldingly back against the pull of theadvancing means, i. e. to impose an accurately controlled tension uponthe advancing strand. Many devices have been made to effect this result,most of which are completely satisfactory for the requirements ofspecific combinations of strand nature, speed of advance, and otherfeatures of a given case. However, none appears to be entirelysatisfactory in all instances. In particular, if the, strand berelatively soft bodied and yet substantially inelastically inextensible,and if the strand, in view of the particular purpose in hand, is beingadvanced slowly, the imposition and maintenance of suitably accuratelyuniform tension of relatively small intensity is a matter of muchdifficulty. Thus in the manufacture of so-called "mandrellated wire, thecontrol of the tension in the relatively large, soft bodied, textilefiber core to effect the slow but uniform advance of the core to andfrom the winding point where a very fine metal wire is served on thecore, must be unusually sensitive and accurate.

An object of the present invention is to provide a device for imposingtension on a longi-- tudinally advancing strand which device shall besimple, compact, reliable and capable of imposing tension of unusuallysensitively and accurately controlled uniformity upon a strand beingdrawn therethrough.

With the above and other objects in view, the invention may be embodiedin a device for imposing tension upon a longitudinally advancing strandand comprising a stationary base, a. lever pivoted upon the base, arigid pinching member mounted on the lever, a friction member to receivethe strand from the pinching member, a resilient second pinching membermounted on the base to press against the strand passing over the firstpinching member, and spring means to urge the first pinching memberagainst the second pinching member and the strand thereon, the partsbeing so arranged that excessive tension in the strand beyond thefriction member will cause the strand to pull the friction member andthereby move the lever against the urge of the spring means to lessenthe pressure on the strand between the pinching members.

Other objects and features of the invention will appear from thefollowing detailed description of one embodiment thereof taken inconnection with the accompanying drawing, in

which the same reference numerals are applied to identical parts in theseveral figures, and in which Fig. l is a, plan view of a deviceconstructed in accordance with the invention, and

Fig. 2 is a View thereof in front elevation.

The embodiment of the invention herein disclosed represents a deviceprimarily adapted to impose delicately and accurately controlled tensionupon a relatively soft bodied strand, e. g. a soft spun thread or cordof silk, being drawn therethrough. The device comprises, in theparticular form shown, a tabular vertically disposed base member lo tobe stationarily supported where needed by any suitable means (notshown). On the front face of the base, a vertically movable lever H ispivoted by means of a bolt 12 and nut l3. The head of the bolt is formedto be a stationary, grooved guide sheave ll. Below the sheave, ahorizontal post l5 mounted in the base Ill carries a. pair of upwardlyand outwardly slanting guide fingers l6, IS. A pinch pin I1 is rigidlymounted in the lever II to the right of and below the sheave I4. A fiat,elastic pinch spring l8 ismounted horizontally on the stationary baseIll to be tangent to and press up against the under side of the pin l'l.Above and to the right of the pin H, a friction peg i9 is rigidlymounted on the lever II. This peg i9 is preferably made, as shown, witha broad, slightly conically tapering circumferential groove 20. Atension spring 2| connected from the outer end of the lever H to asuitable part of the base l0, draws the lever down against the upwardurge of the fiat spring l8 against the pin H. The spring 2| and the thefingers l8, whose function is merely to suppress any whip or variationin direction of approach due to the supply means. From the fingers It,the strand 9- passes over the sheave M, in the groove thereof, thencedown and between the pin I1 and spring l8, and thence to the peg l9. Thestrand is wound-one or more times around the peg IS in the groove 20,and passes thence to the advancing means (not shown). 1

The friction between the strand 9 and the sheave H is negligible. Thefunction of the latter is chiefly to make the strand come to the pin I!all the time at the same place. But between the pin I1 and the spring18, the advancing strand is definitely pinched and thus subjected to africtional force resisting its advance,

which depends for its intensity at any moment upon the position of thelever ll, increasing as the lever falls and diminishing as the leverrises.

In the particular instance here described, the strand 9 is a soft spun,silk thread or cord about 0.022 inch in diameter. This strand is made topass in two complete turns around the peg is in the groove 20, beforepassing away from the device. Since the bottom of the groove is slightlyconical, as shown, these turns around the pe tend to crowd down into thedeeper side of the groove (nearer to the lever) and to leave the pin i1and approach the peg Is at a slight angle which prevents the first turnon the peg from overlapping the second turn, so that the turns on thepeg always lie side by side and cannot pile up and tangle. With theadvancing means pulling the strand away from the peg and the pin i1 andspring l8 resisting the advance of the strand to the peg, the peg actsas a nonrotating capstan or snubbing post and thus exerts a frictionalresistance to the advance of the strand which is constant if allaffective circumstances are constant.

But frictional devices are notoriously subject to partly understoodperturbing effects. Probably minor variations in temperature andhumidity of the neighboring atmosphere aflect the frictional effects ofsuch devices in ways which are not predictably calculable. If this werenot so, it should be theoretically possible to make the lever llstationary instead of movable, and have the device impose uniformtension on I the strand. However, these unpredictable variations dooccur.

The resistance of the strand to the pull of the advancing means, i. e.the tension in the strand, is the sum of the resistances caused by thepassage of the strand around the peg I9 and by the passage of the strandbetween the pin l1 and spring I8. Furthermore, the resistance at the pegI9 is dependent upon the resistance at the pin 11 and spring l8,increasing when the latter increases and diminishing when the latterslackens, because the peg I9 is a stationary capstan.

resistance to advancement between l1 and It is multiplied by the capstaneifect at the peg l8. Hence the combination of these elements in themanner shown affords a remarkably sensitive and swiftly and accuratelyacting, selfgoverning control of the strand tension. The capstan effect,through the lever, controls the pinching effect which, in turn, modifiesthe capstan effect.

The particular device pictured and described above is an illustrativeembodiment of the invention, and may well be variously modified anddeparted from without departing from the spirit and scope of theinvention as particularly pointed out and described in the appendedclaims.

What is claimed is:

1. In an apparatus for imposing controlled tension on an advancingstrand, means to impose friction upon the strand, movably mountedcapstan means to receive the strand from the said means and tofrictionally resist the advance of the strand and to have the back pulltherefor provided by the first named means, and means If, now, thetension between the peg l9 and also diminishes the capstan resistance at'the peg Hi. It is clear, from the characteristic property of capstans,that a small change in the actuable by displacement of the capstan meansto cause variations of the effectiveness of the capstan means to varycorrespondingly the effectiveness of the first named means and therebyto vary the back pull on the strand coming to thecapstan.

2. In an apparatus for imposing controlled tension on an advancingstrand, pinching means to impose friction upon the strand, movablymounted capstan means to receive the strand from the, said means and tofrictionally resist the advance of the strand and to have the back pulltherefor provided by'the pinching means, and means actuable bydisplacement of the capstan means to cause the variations of theeffectiveness of the capstan means to vary correspondingly the effect ofthe pinching means and thereby to vary the back pull on the strandcoming to the capstan. 3. In an apparatus for imposing controlledtension on an advancing strand, a stationary pinching member, a movablepinching member to press the advancing strand against the stationarymember, a non-rotating movably mounted capstan to receive the strandemerging from between the two pinching members which latter therebyprovide the back pull for the capstan, and means actuable bydisplacement of the capstan means to cause variations of theeffectiveness of the capstan to movethe movable pinching member tocorrespondingly vary the pinching effect of the two members on thestrand and thereby to vary the back pull on the strand coming to thecapstan.

4. In an apparatus for imposing controlled tension on an advancingstrand. a base. a lever pivotally mounted on the base, a pinching membermounted on the lever and movable therewith, a second pinching membermounted on the base to coact with the movable pinching member to receivethe advancing strand therebetween, a capstan on the lever to receive theadvancing strand emerging/from between the two pinching members whichlatter thereby provide the back pull for the capstan, and a the twopinching members which latter thereby provide the back pull for thecapstan, and a spring to urge the lever to press the pinching v memberthereon resiliently against the pinching member on the base, the partsbeing so proportioned and arranged that the pull of the strandadvancing-from the capstan tends to move the lever against the urge ofthe spring. JOHN N. SELVIG.

